Modern motor vehicles include a variety of safety features to protect occupants of the vehicle in the event of a collision, including such elements as safety belts, air bags, and front and rear bumpers. Other safety features are provided to provide as much protection as possible to a pedestrian in the event of a vehicle-pedestrian low speed collision (for example, less than 15 kph). As is known, such safety features typically include an energy absorber component. Such energy absorber components intended for impact protection in the event of a vehicle-to-pedestrian impact are typically provided as deformable and/or collapsible elements, designed to absorb as much impact energy as possible early in the impact to maximize pedestrian protection to the extent possible.
Many jurisdictions now include as part of their safety regulations requirements that vehicle hood assemblies be constructed to provide protection to the pedestrian in the event of a vehicle-pedestrian collision. Specifically, these safety regulations include head impact criteria related to the hood of the vehicle. One limiting factor in the design of hoods to meet these regulations is the use of bumpers to meet hood overslam performance requirements. The bumpers provide support, generally along a radiator support near a front of the hood and along fenders near edges of the hood, and absorb road loads while driving and customer usage loads associated with opening/closing the hood (e.g., after servicing the vehicle).
Hood bumpers are typically single piece injection molded parts manufactured in a single durometer or hardness. These single piece/durometer bumpers lack sufficient energy absorption, however, to meet the head impact criteria associated with pedestrian protection. Even more, the bumpers create localized high stiffness areas around the hood at the location of each bumper. These high stiffness areas can lead to design trade-offs between meeting hood overslam performance requirements and pedestrian protection requirements. More specifically, hood bumpers that are too stiff may require positioning outside of pedestrian protection zones of the hood leading to reduced hood system performance relating to both hood overslam performance requirements and pedestrian protection requirements.
Accordingly, a need is identified for a vehicle hood bumper capable of being positioned inside of pedestrian protection zones of the hood while allowing hood system performance relating to both hood overslam performance requirements and pedestrian protection requirements.